Enhanced removal of BTEX/TCE/cis-DCE mixture
using waste scrap tires immobilized with indigenous
Pseudomonas sp.
Q. Lu1, R.A. de Toledo 1, F. Xie1, J. Li1,2, H. Shim1
1Department
of Civil and Environmental Engineering, Faculty of Science and
Technology, University of Macau, Macau SAR, China.
2
College of Natural Resources and Environmental Science, South China
Agricultural University, Guangzhou, China.
1
INTRODUCTION
Waste Tires Recycling
 3 billion car and truck tires are discarded
2%
4%
3%
Fuel
5%
Recycled or used in civil engineering projects
9%
Converted into ground rubber and recycled into products
54%
Converted into ground rubber and used as asphalt
Exported
23%
Recycled into cut/stamped/punched products
Used in agricultural and miscellaneous uses
2
INTRODUCTION
Percentage (%)
50
40
Car tire composition
30
20
10
0
Rubber
Carbon
black
Metal
Additives
Textile
Sulphur
Zinc oxide
Tire component
Two-Phase Partitioning Bioreactor (TPPB) with 10% and 15% (v/v) tires*
Waste tires: sorption phase
2,4-dichlorophenol (83% removal)
4-nitrophenol (~100% removal)
* Tomeia MC, Angeluccia DM, Daugulis AJ (2014) Environ Technol 35:75-81
3
BACKGROUND
 BTEX: Benzene, Toluene, Ethylbenzene, and Xylenes (ortho-,
meta-, and para-)
•
•
•
•
Major monoaromatic components in petroleum products
Industrial solvents and equipment cleansing
Among priority pollutants (US EPA)
Benzene (carcinogen)
 Common source of BTEX contamination:
• Spills from leaking oil tanks
4
BACKGROUND
 Chlorinated Aliphatic Hydrocarbons (CAHs):
• Most widespread contaminants in subsurface
• Cleaning and degreasing solvents
 Perchloroethylene (PCE), trichloroethylene (TCE), dichloroethylenes
(DCEs), vinyl chloride (VC).
 TCE: the most frequently found contaminant in groundwater (US)
 Carcinogen
5
BACKGROUND
Microbial degradation of CAHs:
 anaerobic reductive dechlorination (Dehalococcoides)
 Aerobic cometabolism
6
BACKGROUND
Soil
 BTEX and CAHs:
Water
Biological
Chemical
Physical
 BTEX/CAHs mixture: biological
Cost-effective
Environmental-friendly
Further improvements: CAHs removal
Contaminant mineralization
Hybrid technology (biological + physical)
7
OBJECTIVES
 To remove BTEX/cis-DCE/TCE mixture from
artificially contaminated water using indigenous
bacterial isolate, Pseudomonas plecoglossicida
 To
utilize
scrap
tires
hybrid/enhanced
removal
physical/adsorption
biological/immobilization
(waste)
for
of
mixture;
and
8
MATERIALS AND METHODS
Experimental setup
Microcosms: suspended and immobilized systems
Serum bottle: MSM (mineral salts medium) solution (45 mL)
Contaminants
Inoculum (5 mL)
Scrap tires (1.3, 2.8, and 4.0 g).
Incubation: 150 rpm , 25°C, pH 7, 5 days.
Contaminants concentrations:
• BTEX (300 mg L-1): based on mass fractions in crude oil
(benzene: toluene: ethylbenzene: o-xylene: m-xylene: pxylene at 22.7%: 48.3%: 4.6%: 6.3%: 6.9%: 11.1%)
• TCE (10 mg L-1) and cis-DCE (5 mg L-1)
9
MATERIALS AND METHODS
Adsorption kinetics of BTEX onto tire surface
 Concentrations used in bioremoval experiments
BTEX: 300 mg L-1
TCE: 10 mg L-1
cis-DCE: 5 mg L-1
 Sampling: 0.25, 0.5, 1, 1.5, 24, 48, and 72 h
 Sorption capacity (qe) of adsorbent calculated by:
C0 and Ce, initial and equilibrium concentrations (mg L1);
m, mass of adsorbent (g);
10
MATERIALS AND METHODS
Scrap tires
 Bridgestone (BATTLAX BT-39 tubeless)
 Cut into small pieces (0.2 cm x 0.2 cm x 0.2 cm)
 Weighed and autoclaved for 1 h (121°C, 103.5 kPa)
Microbial culture
 Pure culture of Pseudomonas plecoglossicida
 Isolated from a heavily petroleum-contaminated site (Xiamen, China)
11
RESULTS
Adsorption studies
Benzene
TCE
6
Toluene
cis-DCE
Ethylbenzene
m,p-Xylene
o-Xylene
5
qe (mg/g)
4
3
2
1
0
0
10
20
30
40
50
60
70
80
Contact time (hours)
Adsorption kinetics of individual BTEX compounds (total
concentration, 300 mg L-1), TCE (10 mg L-1), and cis-DCE (5 mg L-1).
Mass of tire: 26 mg/mg.
12
RESULTS
Adsorption studies (each BTEX, 100 mg L-1)
(a)
Benzene
m-Xylene
2.5
Toluene
p-Xylene
(b)
Ethylbenzene
o-Xylene
Multi-solute BTEX
Single-solute BTEX
100
qe (mg/g)
1.5
Octanol-water partitioning coefficient
(Kow)
1.0
3.15 (xylenes and ethylbenzene)
2.73 (toluene)
0.5
Removal Efficiency (%)
2.0
80
60
40
20
2.13 (benzene)
0.0
0
10
20
30
40
50
60
70
80
0
Benzene
Toluene Ethylbenzene m,p-Xylene o-Xylene
Contact time (hours)
(a) Adsorption kinetics of individual BTEX (100 mg L-1).
Mass of tire: 26 mg/mg.
(b) Removal efficiencies for individual BTEX in multi and single solution.
13
RESULTS
Bioremoval by immobilized (attached) microorganisms
Removal efficiency (%) for each compound in mixture under different conditions
after 5 days of incubation
Surface
area
(cm2)
Benzene
Toluene
Ethylbenzene
m,p-Xylene
o-Xylene
cis-DCE
TCE
T1.57.2
70.6±3.2
75.4±2.3
92.8±1.4
92.0±1.1
92.1±0.9
47.0±3.4
54.1±3.4
T3.014.4
84.2±2.1
82.4±1.2
95.6±1.8
96.8±0.4
97.2±0.3
53.7±3.1
64.0±2.8
T4.0 19.2
88.6±1.3
82.8±2.2
98.3±0.3
97.6±0.2
97.9±0.4
64.6±2.2
62.5±2.5
MT1.57.2
99.6±0.2
100
95.5±0.7
96.5±0.3
98.2±0.2
60.0±1.7
70.3±1.7
MT3.014.4
100
100
97.8±0.4
96.3±0.4
98.5±0.3
60.8±2.4
71.6±2.5
MT4.019.2
100
100
100
96.8±0.3
99.0±0.1
61.6±0.9
73.0±2.8
99.5±0.2
97.6±0.1
88.0±0.4
64.5±3.3
56.0±2.7
20.4±1.2
36.3±2.0
BM
•
•
•
•
T: Tire in the absence of microorganisms
MT: Tire with microorganisms
BM: Microorganisms only
1.5, 3.0, 4.0: Different mass of tires
14
RESULTS
Contact angle (93.4±4.1°)
Mean CA versus Time
tiner
97
a
C A
[m e a n ]
96
95
94
93
92
b
91
90
==
89
0,0
0,1
0,2
0,3
0,4
0,5
0,6
0,7
0,8
0,9
1,0
1,1
1,2
1,3
Time [s]
Measurement of contact angle for tire sample over time. Drop volume:
5 L. a) Water drop before experiment; b) Water drop after experiment.
15
CONCLUSION
 Scrap tire (waste) is considered a good candidate
to enhance removal of VOCs such as BTEX, cisDCE, and TCE from liquid phase, due to
remarkable adsorption properties as well as
capability
to
immobilize
(attach/entrap)
microorganisms.
 Further studies are in progress to evaluate whether
the immobilized microorganism possess the same
initial removal efficiency after the reutilization
cycles, including whether higher concentrations of
contaminants can also be applied.
16
ACKNOWLEDGEMENTS
University of Macau Multi-Year Research Grant
(MYRG2014-00112-FST)
Macau Science and Technology Development Fund
(FDCT/063/2013/A2)
Mr. Lu, PhD student; Dr. Li, SCAU/China; Mr. Xie, MS
student
17